Photographic emulsions containing supersensitizing dye combinations



June 10, 1947.- R. B. COLLINS ET AL ,2,422,080

PHOTOGRAPHIC EMULSIONS CONTAINING SUPERSENSITIZING DYE COMBINATIONS Filed Dec. e, 1944 Rolafzdezwaz'd jlilzs Harald welzz'c'i/zso/z INVENToRs l BY l VMM, Ra/*vuoti* 7,7m

Patented June 10, 1947 Pnoroenarino sMULsIons GaN-MINING SiJBEnsENSIHZm G DYE ',LGQlYlBINMIONS Ronald Bernard Collins and `Harold Owen Dickinson, Ilford, England, assigjnors to Ilford Limited, Ilford, Enig-land, a British company Applicaation`theoeinher 6, 194.4SerialNa 566,822 In .Great Britain Decemberfs, 19.43

7 Claims.

This invention `relates to photographic materals and particularly to themanufactureof vdyesensitised .photographic silver halide emulsqrl ,Rhotographic silver .halide Iemulsions have a certain natural sensitivity to light', ybut*l this `is restricted to a short range of wavelengths in vthe ultra-violet .and/or blue regions of the spectrum. 'lhe-.elet `r0f incorporating a Sensitisine dye iS to impart vto the .emulsion .sensitivity .to light of other wavelengths. AIt has .been ,knownforsome time ,that .the .eieot of incorporating two prmore sensitisng dyes in' thefemulsion .isngt valways the simple sum of their individual effects, and sometimes ,an .additional sensitivity itsxobtained Qombinations of dyes whichgive thislatterresult are known as supersensitising combinations.

The present invention is concerned with supersensitising combinations of dyestuffs. According to the invention, photographic silver halide emulsions are supersensitised by incorporating in the emulsion a combination of a sensitising dyestuff of the general formula I.

whereRifRa'Ra'Rs andjRs arethe-same orditferent and are alkyl or aralkyl-g-roups orisu-b'stituted groups of this type, yR4 and Rmarelithesame or diierent and are `hydrogen atoms or alkyl or aralkyl groups, I13g-D2', De. yand =D4 are `the same or different and are residues of heterocyclionitrogen nuclei of the type kcommon in .cyanine dyesand X i and Y areI the same or different and are acidradicles and n is 0 or 1.

In cases where the R groups, or any of them, are alkyl radiales, these .are preferably lower alkyl -rad-c1es, i. .e. containing not A,more than 4 carbon atoms, Ae. g. methyl, ethyl, or hydroxy ethyl radiales, though they may be higher alkyl radicles. In cases where the R groups, or :any .of-them .are aralkyl radcles, lthey may be, Afor example, .benzyl .or ,fnaphthrlmethyl A.raf-icles- :substituted,alkyhradicles which may he present, e. Le. asr envoi' R1, R2, R5 and .136, may flO-e ,hy-

, droxy;alkyl radicles.

mhezresduesiDtIDaDa andDemay-.rbezselsted drom :the 'residues yof-f-i'fhazoles,. Qxazoles, ,selenazoles and their polycyclic Vhoinologues,vsiiollnas those .er rthe benzene, ,naphtilaleneecnerzlitlleae andanthracene series .pyridine audits ,PQlYPyQlie homologues. anchas elflinqlne and e erlldnalihihaquinqlines `lepdifnes. .inddenines `da such .as .pyrimidines `and .Quineolns CllZQlES (e. g. thio-.diazole), oiga; vings, ,thiahz'qlines and selenazolines. The polycyclic compoundsfof this series may also ,be substituted in the car- 13.905 Clic Tng With 011.5 911mm? .g'OllPs .Such as alkyl, aryl, tillllp, ,hYET0XY,.21 k0XY 31,1@- methyleee-.dioxv swims. .er :by belegen atoms- Theacidl radiales .X .and .Y ,maybe for exemple, selected .from halogenide radiclea e. g. chloride, @melide ...and .iQdida er alkyl Sulphate alkyl P'- toluene Sulrheate .0r perchlorate.

Dyestuffs of the general formula 5I, and their preparaten, aresiestrihedin Britishpatentspecification No. 553,144 land corresponding `'lllriitei States entlsst@ 'eris11fNumber 4611,3241391 October 195i?. .Dyestuis of the gener-alformu-lall are wellknown and may be synthesised by any ofthe-knownjmethods.

The following are examples of specific -dyestuis which maybe employed, the dyestu-fls being .lettered to facilitate rsubsequent reference:

Dyestus of general formula I iodide.

H. a2 `1 .9Y trmethyl thiaquinodicarbocyanine iodide- I. 53.3;9,12; ;tetrarnethyl -gthiadiarbooyanine mite.

vDyestws of v general Aformula [I1-I ,Aanine chloride.

,S- 3!fdiethylzthiacarbocvanne iodide.

,'ieciciycmsyetny1 femenin- .tratareportions equivalent to to 50 cc. of a 1 in 2000 Y' solution of the dyestui per litre of emulsion 'are suitable. The dyestuffs are preferably incorporated in the emulsion during the manufacture of the emulsion. t Y The Yfollowing examples illustrateY the invention. In these examples the emulsions containing the dyes were tested for speed to daylightandto A The dyestuifs of general formula red" light. II, when used alone, do not impart any sensitivity Y 4 Y sion as shown by the generally increased daylight speed. Y Y

This general eiect is illustrated in the accom panying drawings which show spectral sensitivity curves for the emulsions of certain ofthe foregoing examples.

In these drawings, Fig. 1 shows thespectral Y sensitivity curve of the emulsionof Example laV .('full line) and 1b (dotted line), Fig. 2'shows the -spectral sensitivity curve of the emulsion of EX- ample 6a- (full line) and 6b (dotted line), Fig. 3

j shows the spectral sensitivity curve of the em'ul tothe emulsion at wavelengths above'680 my,

so that by exposing the supersensitised emulsion through a kilter which cuts ofi' allradiation of wavelengthsk less thanY 680V mp, thev red speed of the emulsion may be determined and this, in

comparison with an emulsion'containingV only aY dyelof -general formulaI, affords a measure of the supersenstising effect.

` Examples V VIn these examples the dyestuffs employed are referred to by the lettering given above. .'Ihe combinations of dyestus-were incorporatedjin 'a gelatin silver iodobromide emulsion con-taining about 6.5 gms. of silver halidev (icalculatedas silver)VV per litre of emulsion, during the manufacture of the emulsion, and the resulting emulsion was coatedY on glass and its speed determined to daylight and also to red light,v i. e.- of wavelengths above 680 mp.. Y The resultsfobtained are set out in the following'table (in which the quantities of dyestuff are given as ccs. of a 1 in 2000 solution Vof the dyestuff added per litre of emulsion) K 1 i I Quantity Quantity j Exam- FDglfa of Dye of Flgfa of dye of 9g.; Red ple No. or Formula Y Formula f 1g Speed l Y I .II II Speed A .1.40, 2.0 'A 250 64 'A 150 32 B Y. 100` 18 B 200 34 B Y 89 14 B 150A 25 E 140 2. 1 E 240 9.' 7 C `250 42 C 470 Y 89 C 74 l2 o 26ol 45 C 10o 21 C` 270 45 Y D 74 2.8 D 170 27 Y D 27o sa e of the dicarbocyanine dye,l but actually effectV an increasey in the overall sensitivity of the `emulsionY of VExample/9a, (ullline) and V9b (dotted line), Fig. 4V shows-the spectral sensitivity curve of the emulsion of Example .3a (full line) and 3b (dottedline), Fig. 5 shows the spectral sensitivity curve of the emulsion of Example la (full line)` vand 4b (dotted line), and Fig. 6 shows the spec-V tral sensitivity curve of the emulsion of Example 5cl-(full line) and 5b (dotted line) YTliedyesof Ygeneral formula'QII, used inthe foregoing examples do not, whenused alone,` impartV anyv sensitivity to the emulsion over-Wavelengths longer thank 680mg so thatV the 4curves Clearly demonstrate the Vsupersensitising' e'ect 'obtainedv Y -While this Vinvention is of particular ValueV in connection "with the supersensitising of silver halide emulsions in gelatin, other bindingrrcolloids for Ythe emulsion fmay be employed, K for-example polyvinyl alcohol, polyvinyl acetals, far-hydro lysed cellulose esters and the like. V What we claim is: 1. vA photographic silver halidefemulsion con- 27; A photographic silver halide emulsion,r4 coni taining bothV a ysensitising dyestuff offrthe'zforwhererR1, L12.2.7523, RsV and ReY are eachjseleeted fromY the group consisting of alkyland'k aralkyl groups, R4 and Bn lare Yeach selected from Vthe group consisting of the hydrogen atom and alkyl andraralkyl groups, D1, D2, DaanduDilarerresi'- Vrdues of-azo1e nuclei,- andA X`an'dA Yjare. .acid

radi/,cles andv isa-number taken` from the group consistingofand 1.? u

3. A photographic silver halide emulsion containing both a sensitising dyestuft of the formula:

where R1, Rz, R3, Rs and Re are each selected from the group consisting of alkyl and aralkyl groups, R4 and R1 are each selected from the group consisting of the hydrogen atom and alkyl and aralkyl groups, Z1, Z2, Z3 and Z4 are selected from the group consisting of oxygen, sulphur and selenium atoms, and M1, M2, M3 and M4 are residues completing azole nuclei.

4. A photographic silver halide emulsion containing both a sensitising dyestuff of the formula:

^ where R1, R2, R3, R5 and Re are each selected and a sensitising dye of the formula:

where R1, R2, R3, R5 and Re are each lower alkyl groups, R4 and R1 are selected from the group consisting of hydrogen and alkyl and aralkyl groups, and Z1, Z2, Z3 and Z4 are each selected from the group consisting of oxygen, sulphur and selenium atoms.

6. A photographic silver halide emulsion containing both a sensitising dye of the formula:

and a sensitising dye of the formula:

Where R1, R2, R3, R5 and Re are lower alkyl groups, and R4 and R1 are selected from the group consisting of hydrogen and alkyl and aralkyl groups.

'7. A photographe silver halide emulsion containing both a sensitising dye of the formula:

S Ra and a sensitising dye of the formula:

C=Cn- \N/ N n, R/ \Y where R1, R2, Ra, R5 and Re are lower alkyl groups, and R7 is selected from the group consisting of hydrogen and alkyl and aralkyl groups.

RONALD BERNARD COLLINS. HAROLD OWEN DICKINSON.

REFERENCES CITED The ollowing references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,075,048 Mees Mar. 30, 1937 2,104,064 Zeh Jan. 4, 1938 

